Today Ethernet is the dominant computer networking technology for local area networks (LANs). As Ethernet gains wide popularity among enterprise, carriers, and cloud service providers, Ethernet architecture has transitioned LAN segments from being implemented as passive shared mediums only to being implemented as actively switched networks. Over the years, numerous protocols have been implemented in actively switched networks for Ethernet frame forwarding. For example, a variety of spanning tree protocols utilizes flood-and-learn schemes, where frame forwarding is carried out largely in a data plane. Later shortest path bridging (SPB) protocol adopts a different approach, where a node in a SPB network contains link states of the network thus frames can be forwarded along a shortest path without resorting to flood-and-learn. As Ethernet is used in more networks, more applications need forward frames across networks supporting different frame forwarding protocols, and internetworking for frame forwarding is a challenge.
Multiple media access control (MAC) registration protocol (MMRP) is an application of multiple registration protocol (MRP), which replaced generic attribute registration protocol (GARP). MMRP operates at the Data Link Layer at the Open Systems Internnection (OSI) model and it registers MAC addresses on network devices in an Ethernet network. MMRP is originally defined in IEEE 802.1ak-2007 and subsequently included in 802.1Q-2011. It replaced the 802.1D based GARP multicast registration protocol (GMRP). MMRP collects information nodes interested in reception of frames destined to a particular MAC address (e.g., a group MAC address), and frames destined to the particular MAC address within an MMRP compatible network will then be forwarded to all the interested nodes within the network.
As Ethernet grows to become ubiquitous, a frame may go across networks supporting different frame forwarding protocols. An MMRP compatible network needs to be able to forward frames destined to and accept frames sourced from a network that does not support MMRP natively. In other words, MMRP registration information regarding an application needs to be shared with a non-MMRP network.